GB1431585A - Time division multiplier system - Google Patents

Abstract

1431585 Multiplex data transmission INTERNATIONAL BUSINESS MACHINES CORP 3 July 1973 [10 July 1972] 31689/73 Headings H4P and H4L In a time multiplex data transmission system wherein information, transmitted in variable length frames, is distributed to selected terminals, each frame consists of a synchronizing character followed by address information, followed by one fixed length unit of information for each channel. Data received on line 1 is demodulated in MODEM 2 and is fed to a reception control unit 10 (detailed in Fig. 3, not shown). Each of the terminals, e.g. T i , to which data is to be passed includes a shift register 5 and by-pass switch 4, the registers of all terminals being connected in series to the unit 10. The address information of a frame is detected by unit 10, which produces signals to open the switch 4 in all terminals which are to receive data during that frame and this data is then shifted through the series connected registers, until each register contains its relevant data unit. A further control signal then reads out the contents of each register into its associated memory store 6. The contents of each memory are then serialized in unit 7 and fed to the related MODEM 8. For transmission in the reverse direction, data from the terminal lines, e.g. line 11, is fed via MODEM 8 the memory 13 to another register 14 shunted a further switch 15. The switches 15 of all registers 14 containing data are then opened by transmission unit 20 (detailed in Fig. 5, not shown) and their contents are read out and assembled into frames together with address signals and synchronizing signals.